The broad objective of this proposal is to understand how stringent amino acid control operates to regulate the expression of an appreciable fraction of E. coli genes. Using a selected ribosomal cistron promoter region, a sizeable degree of definition of promoter chrarcteristics have been possible. It seems that a fairly thorough understanding of the structure and activity of the ribosomal promoter would be needed for further studies on its control. The aims of this proposal are to sequence the in vitro RNA transcripts directed by two tandem ribosomal promoters, with special emphasis on the region between the two promoters. This information should check on sequencing the DNA fragment carrying the two promoters as well as a means of estimating promoter heterogeneity in 30S rRNA precursor from whole cells. Further work correlates structure of the DNA with the specific characteristics of the transcriptional control of these promoters. KEY WORDS: Cloned ribosomal promoters, RNA and DNA sequencing, control of transcription.